|Publication number||US7463127 B2|
|Application number||US 11/077,725|
|Publication date||Dec 9, 2008|
|Filing date||Mar 11, 2005|
|Priority date||Nov 14, 2002|
|Also published as||US6960974, US20040095218, US20050156591, WO2004045075A1|
|Publication number||077725, 11077725, US 7463127 B2, US 7463127B2, US-B2-7463127, US7463127 B2, US7463127B2|
|Inventors||Hong Wan, Edgar R. Mallison, Michael L. Freeman|
|Original Assignee||Honeywell International Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (13), Non-Patent Citations (4), Referenced by (1), Classifications (19), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation of U.S. application Ser. No. 10/294,105 filed Nov. 14, 2002 now U.S. Pat. No. 6,960,974.
The present invention relates to a highly reliable switch that has no contact with a moving object and that is capable of detecting its own failure and/or over travel range.
Switches are used in a variety of applications to control the on and off states of loads, to sense the proximity or position of input devices, to provide inputs to data processing systems, and so on. Many of these applications involve complex systems, such as those used on aircraft or oil wells, which rely on a large number of switches. Many of these switches experience intensive use in these systems and, as a result, fail because their parts simply wear out. Switches can also fail because they are driven or otherwise travel out of range.
Many of the switches used in complex systems provide critical functions. When a switch that provides a critical function fails, the failure can result in a potentially dangerous and/or economically costly condition. Therefore, when such a switch fails, it is important to replace it as soon as possible in order to avoid or minimize the potentially dangerous and/or economically costly condition. However, when a switch fails in a complex system, it can be very difficult to locate it so that it can be replaced.
The switch of the present invention is a non-contact position sensor with a built in self-diagnostic system. The self diagnostic system can indicate that the switch travel out of range and/or that the switch is not functioning properly. This switch has less wear because it does not contact the object that it is sensing, and there is less chance that this switch will travel out of range. Therefore, the switch of the present invention has a longer life. Also, this switch detects when it has failed so that it can be easily located and replaced.
In accordance with one aspect of the present invention, a smart switch comprises a magnetic operator, at least one magnetic sensor located to sense movement of the magnetic operator, and a processor arranged to process an output of the magnetic sensor so as to detect an over travel range and a normal operating range of the magnetic operator.
In accordance with another aspect of the present invention, a smart switch comprises a magnetic operator, first, second, and third magnetoresistive sensors located to sense movement of the magnetic operator, and a processor arranged to process outputs of the first, second, and third magnetoresistive sensors so as to detect right and left over travel ranges and a normal operating range of the magnetic operator.
In accordance with still another aspect of the present invention, a smart switch comprises a magnetic operator, a single magnetoresistive sensor located to sense movement of the magnetic operator, and a processor arranged to process an output of the single magnetoresistive sensor so as to detect an over travel range and a normal operating range of the magnetic operator.
These and other features and advantages will become more apparent from a detailed consideration of the invention when taken in conjunction with the drawings in which:
As shown in
As the switch operator 20 passes over it, each of the magnetoresistive sensors 12, 14, and 16 is mounted on the mounting surface 18 so as to produce a corresponding one of the voltage outputs 22, 24, and 26 shown in
For example, each of the magnetoresistive sensors 12, 14, and 16 may be a HMC1501 or HMC1512 supplied by Honeywell International, the magnetoresistive sensors 12 and 14 may be separated on the mounting surface 18 by a distance of 2-40 mm, and the magnetoresistive sensors 14 and 16 may be separated on the mounting surface 18 by the same distance. Also, the switch operator 20, for example, may be a magnet or other magnetic field generating device. Given these devices and distances, the magnetoresistive sensors 12, 14, and 16 produce the voltage outputs 22, 24, and 26 relative to the travel of the switch operator 20 along the mounting surface 18 from one end to another.
As shown in
The comparator 30 has a threshold set so that it switches on when the voltage output 22 is below a first threshold, such as 0.05 volt, so as to provide an output at a level 40 of the waveform 38. The signal from the amplifier 32 at this point is comparatively smaller than a predetermined value so that the logical gate 36 passes the level 40 and none of the outputs from the amplifier 32 and the comparator 34.
As the voltage output 22 rises sufficiently, the comparator 30 switches off at a point 42. Because the comparator 34 is still off at this point, only the output of the amplifier passes through the logical gate 36. Accordingly, only the amplified voltage output 24 contributes to the output of the logical gate 36. The output of the logical gate 36 during the time that both the comparator 30 and the comparator 34 are off is the portion 44 of the waveform 44.
The comparator 34 has a threshold set so that it switches on when the voltage output 26 is sufficiently large so as to provide an output at a level 46 of the waveform 38. The signal from the amplifier 32 at this point 48 is now comparatively smaller than the level 46 so that the logical gate 36 passes the level 46 and none of the output from the amplifier 32 and the comparator 30. Accordingly, the output of the logical gate 36 holds at the level 46.
Additionally, when the output from the switch 10 below a predetermine threshold is detected, or when the outputs from the three magnetoresistive sensors 12, 14, and 16 do not follow the expected pattern, it can be determined that the magnet or other magnetic field generating device of the switch operator 20 has fallen off of the actuator, or that the switch operator 20 has otherwise malfunctioned, or that the switch 10 has become disconnected from its processing circuit such as shown in
As shown in
As shown in
Additionally, by detecting that the output from the magnetoresistive sensor 82 is below a predetermine threshold, or when the output from the magnetoresistive sensor 82 does not follow the expected pattern, the processor 88 can determine that the magnet or other magnetic field generating device has fallen off of the switch operator 86, or that the switch operator 86 has otherwise malfunctioned, or that the switch 80 has become disconnected from the processor 88.
The embodiment illustrated in
Certain modifications of the present invention have been described above. Other modifications of the present invention will occur to those practicing in the art of the present invention. For example, instead of using the microprocessor 66 to process the signal shown in
Moreover, the outputs of the magnetoresistive sensors 12, 14, and 16 may be processed by apparatus other than that specifically described above in order to process the voltage outputs 22, 24, and 26 and to detect over travel, magnet loss, or other failures of the switch 10.
Also, it is also possible to use more than three sensors in order to extend the travel range. In this case, the outputs from the middle sensors can be combined and the processor can be used to determine the position.
Furthermore, the processing arrangements shown in
In addition, the switch 10 is described above as including magnetic sensors in the form of the magnetoresistive sensors 12, 14, and 16. Instead, these magnetic sensors may be other types of magnetic sensors such as anisotropic magnetoresistive sensors, giant magnetoresistive sensors, Hall sensors, etc. Similarly, the magnetoresistive sensor 82 may be an anisotropic magnetoresistive sensor, a giant magnetoresistive sensor, a Hall sensor, etc.
Moreover, temperature compensation may be provided for the switches described above. For example, the microprocessor 66 may store a number of temperature coefficients that are accessed depending on the temperature of the switch as sensed by a temperature sensor 90 shown in
Accordingly, the description of the present invention is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which are within the scope of the appended claims is reserved.
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|Citing Patent||Filing date||Publication date||Applicant||Title|
|US20130320970 *||May 31, 2012||Dec 5, 2013||Allegro Microsystems, Inc.||Gear tooth sensor with peak and threshold detectors|
|U.S. Classification||335/215, 335/207, 340/547|
|International Classification||G01R33/06, G01D5/14, H03K17/97, G01D3/08, G01R33/02, H01H67/00, H01H55/00, H01F7/02, G01B7/14, G01B7/30, H01H9/00, H01F7/00|
|Cooperative Classification||G01D3/08, G01D5/14|
|European Classification||G01D5/14, G01D3/08|
|Jul 23, 2012||REMI||Maintenance fee reminder mailed|
|Dec 9, 2012||LAPS||Lapse for failure to pay maintenance fees|
|Jan 29, 2013||FP||Expired due to failure to pay maintenance fee|
Effective date: 20121209